1. Field of the Invention
The present invention is directed to methods and compositions to control parasitic mites of honey bees and methods and compositions to control hive invading pests.
2. Description of the Art
Honey bees are necessary to pollinate important agricultural crops and also to produce honey and wax for commercial markets. In the United States, honey bees produce $270 million worth of honey, beeswax, and other hive products and pollinate over $14 billion worth of crops annually.
Parasitic mites are economically important parasites of honey bees which affect honey bee populations worldwide. Varroa jacobsoni (Oudemans) (=V. destructor) (Acari: Varroidae) are small crab-shaped parasitic mites that are found attached to adult bees or under capped brood cells where they reproduce. In either case, Varroa feed on hemolymph by puncturing the exoskeleton of the bee with their mouthparts.
Varroa reproduction begins when the adult female enters a brood cell shortly before it is capped. The female must feed on larval hemolymph before she can lay eggs. The Varroa eggs eclose under the sealed cell, and the developing mites feed on the bee pupa. The first egg laid by the female Varroa develops into a male. Subsequent eggs develop into females that mate with their brother. The mated female mites along with their mother are released from the capped cell when the bee emerges. These mites will hereinafter be referred to as “phoretic mites.” The females attach to adult bees between the abdominal segments or between body regions, making them difficult to detect. These are also places from which they can easily feed on the bees' hemolymph. Adult bees serve as intermediate hosts when little or no brood is available and as a means of transport.
Varroa mites reduce bee longevity. When infestation levels are high, entire colonies die. Varroa are also believed to damage honey bees due to transmission of at least six bee viruses. Spread of Varroa mites among colonies can occur due to several factors, including commercial transport of bees and queens, the migratory activities of beekeepers or swarms that may fly long distances.
Maintaining a supply of strong honey bee colonies available for pollination is essential for the sustained production of crops worth more than $14 billion to the U.S. farm economy. Current control measures for Varroa include synthetic pesticides. Introducing lipophilic pesticides into honey bee colonies not only contaminates the comb, but opens the possibility of contamination of honey and pollen which are sold to the public.
Presently there is one EPA-registered product under Section 3 of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) for control of Varroa mites: a plastic strip impregnated with the contact synthetic pyrethroid pesticide fluvalinate (Apistan® strip, Wellmark International). There is also one EPA registered product under Section 3 of FIFRA for suppression of Varroa mites: a 65% formic acid gel (Apicure®, Apicure, Inc., believed to be the device of U.S. Pat. No. 6,037,374). In 1999 and 2000 EPA issued an emergency authorization, under Section 18 of FIFRA, for use of the organophosphate coumaphos (CheckMite+™, Bayer Corp.) for control of Varroa mites. Formic acid and coumaphos are in EPA toxicity category I which requires the signal word “Danger.” Fluvalinate is in EPA toxicity category III which requires a signal word of “Caution.” 2-Heptanone is also in toxicity category III.
Of serious concern is the fact that Varroa mite resistance to fluvalinate, the most commonly used miticide, has been reported in Europe (Milani, Apidologie 30:229-234 (1999); Vedova et al., Ape Nostra Amica 19:6-10 (1997)) and in the United States (Elzen et al., American Bee Journal 138:674-676 (1998); Elzen et al., Apidologie 30:13-18 (1999)). Also, fluvalinate residues have been detected in foundation beeswax used in bee colonies. Resistance to coumaphos is also now being reported. Further, coumaphos, which is also lipophilic, poses the threat of contaminating hive product. The formic acid compositions are effective against tracheal mites but are reported to have limited effectiveness against Varroa. Packaging problems have been reported for the formic acid compositions.
To avoid some of the potential problems related to pesticide use in beekeeping, some researchers are selecting strains of bees that tolerate or are resistant to mites. These selection programs take several years, and those colonies that are susceptible to mites will be lost in the interim. Beekeepers need immediate relief from Varroa infestations that already exist in their colonies. What is needed are safe and effective ways to control parasitic mites of bees.
Hive invading pests inflict substantial economic losses to beekeepers. One of the most damaging pests to the bee industry is the greater wax moth (Galleria mellonella). Currently there is no registered means of controlling this pest. The small hive beetle (Aethina tumida), is another destructive pest. There are no known natural enemies of the small hive beetle in the United States. As discussed below, other hive invading pests include ants and the parasitic mite Tropilaelaps. What is needed are safe and effective ways to control hive invading pests.
2-Heptanone is a pheromone produced by the mandibular glands of adult worker honey bees, Apis mellifera and Apis cerana (Vallet et al., J. Insect Physiol. 37(11):789-804 (1991); Sakamoto et al., Journal of Apiculture Research 29(4):199-205 (1990)), older than 8-10 days. The opening of the mandibular gland is inside the buccal cavity (mouth) of the bee at the base of the mandibles. 2-Heptanone is produced continuously and is universally distributed throughout the bee colony and in the wax. It is believed that the primary function of 2-heptanone in the honey bee hive is that of the principal universal solvent used by the bees to manufacture bees wax comb and propolis (bee glue used to suspend wax combs and plug holes). The bees secrete 2-heptanone while they use their mandibles to masticate (chew) the tiny wax flakes produced by their abdominal wax glands. The wax flakes are formed into uniformly thin wax sheets that are used to build the solid hexagonal wax walls of honey comb cells. Worker bees also gather a variety of plant resins which are solubilized with 2-heptanone and either painted on the surface of the wax honey comb or mixed with wax to produce propolis. A new layer of propolis is painted in brood cells during cleaning after each brood cycle. The net result is that 2-heptanone is incorporated into the structure of the hive interior.